475 Ansari, M., Shekari, F., Mohammadi, M.H., Biró, B. and Végvári, G. (2017), Seed Sci. & Technol., 45, 475-484. https://doi.org/10.15258/sst.2017.45.2.02 Improving germination indices of alfalfa cultivars under saline stress by inoculation with beneficial bacteria M. ANSARI 1,2 , F. SHEKARI 1 *, M.H. MOHAMMADI 1 , B. BIRÓ 2 AND G. VÉGVÁRI 2,3 1 Department of Agronomy and Plant Breeding, Faculty of Agriculture, University of Zanjan, Zanjan, P.O. Box 313-45195, Iran (E-mail: shekari@znu.ac.ir) 2 Department of Soil Science and Water Management, Szent István University, Budapest, Hungary (E-mail: biro.borbala@kertk.szie.hu; vegvari.gyorgy@kertk.szie.hu) 3 Institute of Physiology, Biochemistry and Animal Health, Kaposvár University, Hungary (E-mail: vegvari.gyorgy@ke.hu; vegvari.gyorgy@kertk.szie.hu) (Accepted March 2017) Abstract Salinity stress is one of the most significant factors affecting seed germination of alfalfa. In this study, we considered whether it is possible to reduce the deleterious effects of salinity by inoculating seeds with beneficial salt-tolerant bacteria. Seeds of nine alfalfa cultivars were inoculated with two beneficial bacteria, Pseudomonas sp. Proradix and Hartmannibacter diazotrophicus. Salinity stress reduced the germination indices in all nine alfalfa cultivars significantly. Inoculation with either bacteria could improve germination performance through increasing germination percentage, germination index, radicle length, plumule length, seed vigour and seedling fresh weight. Germination indices decreased in most cultivars at > 10 dS m -1 salt concentration (without inoculation), but were high at 20 dS m -1 (inoculation with either bacteria). Germination indices were improved by both the bacteria, however, germination percentage, germination index, plumule length and seed vigour were most improved by inoculation with Pseudomonas sp. Proradix; seedling fresh weight and radicle length were most improved by Hartmannibacter diazotrophicus. It is suggested that the bacteria could be used to inoculate alfalfa seeds and solve the problem of germination under saline conditions. Introduction Salinity stress is one of the most significant limiting environmental factors, affecting plant production in more than 34 million hectares of agricultural lands. Saline soil increases day by day because of unsuitable agricultural practice, using saline water from saline rivers for plant irrigation, low precipitation, high surface evaporation especially on dry lands, and weathering of native rocks such as basalt (Munns and Tester, 2008; Gupta and Huang, 2013). Salinity stress causes reduced water absorption of seeds by decreasing water osmotic potential and inducing osmotic stress (Munns, 2002). The toxic saline ions distort cell division, cell expansion and metabolic processes, and decreases germination percentage, seedling growth and, ultimately, all developmental stages (Zhu, 2001). If seeds can germinate under saline conditions, growth and survival could increase (Hubbard et al., 2012). * Author for correspondence